Reflective insulation of the type comprising a laminate of aluminum foil and fiber glass insulation has been used as attic insulation for some time. It is primarily used in areas of low winter temperatures and is conventionally installed over or between the joists with the foil side down so that heat radiating up from the room below will be reflected back, thus reducing heat loss through the ceiling. Typically, laminates of aluminum foil and kraft paper are used instead of plain aluminum foil, with the kraft paper side of the laminate being attached to the fiber glass insulation by an asphaltic hot melt adhesive. The foil surface of such products is applied face down against the gypsum board ceiling, since if the foil surface is left exposed the asphaltic adhesive near the foil surface would crate a potential fire hazard. Such foil-kraft laminates are generally comprised of aluminum foil having a thickness of 0.00025 to 0.00035 inch, laminated to kraft paper weighing 30 to 40 pounds per ream.
In addition, reflective foil barriers are used in attics to reflect the radiant energy of the sun which passes through the roof. Reflective foil barriers are particularly useful in warmer climates where air conditioning is frequently used. By the addition of a reflective foil barrier to the attic, a large portion of the radiant energy from the sun is prevented from entering the house, thereby reducing the need to operate the air conditioner. For a reflective barrier to be effective, it must be installed in a space protected from the natural elements. An air space adjacent to the exposed foil surface is necessary to reflect the radiant energy.
Prior art reflective foil barriers are comprised of thick aluminum foil, metallized plastic films, or thin aluminum foil laminated to a carrier sheet. Such barriers are typically laid over the top surface of existing attic insulation, stapled to the underside of the roof rafters before the roof decking is installed, or laminated to the underside of the roof decking.
In instances where plain aluminum foil is used, no fire hazard is encountered, but the foil must be relatively thick, in the order of 0.01 to 0.04 inch, to give the foil enough toughness to enable it to be applied without tearing and installed without being damaged. Such a product is expensive due to the substantial quantities of foil required. It can also be hazardous to handle due to the extremely sharp edges of the foil.
In instances where foil is laminated to a carrier sheet, such as kraft paper, or where the aluminum is metallized onto a plastic film, a fire hazard is presented due to the flammability of the paper or plastic film component. In cases where the fire hazard has been minimized, the cost of the reflective barrier product becomes quite expensive. In addition, the prior art requires installation of a radiant barrier to be a separate procedure from installation of other insulating materials such as fiber glass.
Prior to this invention, a satisfactory inexpensive solution to fire hazards and ease of installation had not been offered.